The present invention relates generally to interferometry and more specifically to a symmetric circular magnetic waveguide for cold neutral atoms using current carrying wires on a microchip. The waveguide is ideal to make an ultra-sensitive gyroscope using atom interferometry and the Sagnac effect. Either cold thermal atoms, quantum degenerate gasses (e.g. Bose-Einstein condensates, BECs), or molecules with a magnetic dipole moment may be used. This technology can also be used in general inertial force sensing (accelerometers, gravimeters), atomic clocks, electromagnetic field sensing, and quantum computing.
Important background to the present invention is found in the following U.S. patents of interest that are incorporated herein by reference are:
U.S. Pat. No. 6,476,383 Esslinger, et al. Nov. 5, 2002 entitled Device and method for generating and manipulating coherent matter waves; and
U.S. Pat. No. 4,874,942 Clauser Oct. 17, 1989 entitled Rotation, acceleration, and gravity sensors using quantum-mechanical matter-wave interferometry with neutral atoms and molecules.
Patent No. 03761721 Altshuler Sep. 25, 1973 entitled Matter wave interferometric apparatus.
The Esslinger and Clauser references are of interest in that they set forth how a neutral atom (and/or molecule) matter-wave interferometer (and/or set of interferometers) can be used as an inertial sensor with a sensitivity exceeding that of conventional mechanical sensors and multiple circuit optical interferometers (including ring lasers) by many powers of ten. An interferometer in which matter-wave propagation beam paths enclose a finite area will sense rotations via the Sagnac effect. One with the paths displaced from each other will sense acceleration plus gravity. The matter-wave energy and mass dependence of the phase shifts that are due to rotation and acceleration are different. Thus a pair of interferometers with different energies and/or masses can perform simultaneous independent measurements of rotation and acceleration.
Atom interferometry with cold neutral atoms (<1 mK) promises to revolutionize the field of inertial force sensing. DeBroglie wave interferometers using cold neutral atoms have already produced state of the art clocks, gyroscopes, accelerometers, and field sensors since the invention of laser cooling and trapping and the Magneto-Optical Trap (MOT) in the 1980's. In general, these devices have been made in free space (i.e. the atoms are not trapped) and have very large power, space, and weight requirements. The growing field of atom interferometry on a microchip, with the creation of BEC on a microchip in 2001 (See Hansel et al, Nature v. 413 p. 498), gives hope that one can make a sensor with all the advantages of cold atoms without the large power dissipation and volume/weight requirements. These microchip devices use captive atoms with a magnetic dipole moment which are trapped by magnetic field gradients produced by currents on the microchip.